# testhost TODO Tracks known gaps and future work for `tools/testhost/`, the generic headless plugin test host (see `README.md` for what it does and how to use it, and `/home/jens/.claude/plans/sharded-finding-tower.md` for the original design plan). Nothing here blocks current use — Phases 1-4 of the plan are done and verified (PR https://git.jayfield.org/jens/JaySynth/pulls/1). ## Deferred by design (Phase 5 of the plan) - [ ] **LV2 plugin format support.** JUCE 3.1.1 (the version currently vendored at `sdk/juce/JUCE-3.1.1`) has no LV2 hosting backend. Once JaySynth's own JUCE dependency is upgraded (or a custom `AudioPluginFormat` subclass is written against the current version), register it in `PluginHost`'s constructor alongside `VSTPluginFormat` - no other host code should need to change, since everything downstream talks to the format-agnostic `AudioPluginInstance`/`AudioProcessor` API already. - [ ] **VST3/LADSPA format support.** JUCE already ships `VST3PluginFormat`/`LADSPAPluginFormat` in this same vendored version - registering them is a one-line addition to `PluginHost`'s constructor, just not done yet since nothing has needed it. - [ ] **Windows build (`Makefile.win`).** The plan calls for mirroring `src/plug`'s Linux/Windows Makefile pattern; only the Linux side has been built and tested so far. ## Test coverage gaps - [ ] **Only mono (1 in/1 out) and asymmetric (2 in/1 out) effect channel configs have been smoke-tested** (`ZamDelay-vst.so`, `ZamComp-vst.so`, `ZamEQ2-vst.so`). A genuinely stereo-in/stereo-out effect hasn't been run through yet - worth doing before relying on this tool for a stereo effect plugin specifically. - [ ] **No automated regression baseline comparison.** The plan's stretch goal: batch-render every `.fxp`/`.xmp` under `extras/sounds/` through a fixed note pattern and diff against stored baseline WAVs/checksums, to catch DSP or save-load regressions automatically instead of via one-off manual runs. Not built. - [ ] **No CI wiring.** Nothing currently runs `testhost` automatically on push/PR; it's a manual, opt-in tool for now. - [ ] **No unit tests for `TestScenario`'s JSON parsing itself** (malformed JSON, missing required fields, wrong types, out-of-range values) - only exercised indirectly via a couple of hand-written scenario files during development. Edge-case handling (e.g. a negative `sample`, an unterminated `noteOn` with no matching `noteOff`) is untested. - [ ] **Polyphony/multiple simultaneous notes untested** - only ever a single held note in all smoke tests so far. ## Investigate - [ ] **JaySynth's compiled VST2 wrapper never advertises chunk support to the host, so real `.fxp`/`.fxb` sample files silently have no effect when loaded generically.** Found while building `tests/run_tests.sh`: loading a bundled sample under `extras/sounds/` via `--patch` produces byte- identical output to not loading anything (confirmed by diffing `--printParams`). The files are legitimately in VST2's opaque-chunk ("FPCh") format, but JUCE 3.1.1's plugin-side VST wrapper (`juce_VST_Wrapper.cpp`, compiled into `JaySynth.so`) never sets `effFlagsProgramChunks` on the `AEffect` struct, so JUCE's own host-side `VSTPluginInstance::usesChunks()` returns false and silently no-ops both load and save. Not one of the tracked `TODO.md` (repo root) findings, and not attempted here - fixing it means patching JUCE's own VST wrapper, a bigger and riskier change than this pass's scope. See `tests/README.md` for the full writeup; `tests/run_tests.sh`'s round-trip tests work around it by using `testhost`'s own save output as the fixture instead of an external sample file. - [ ] **DPF-based plugins print a non-fatal assertion on load.** All three Zam*-vst.so plugins tested (built with the DISTRHO Plugin Framework) print `assertion failure: "fIsActive" in .../DistrhoPluginInternal.hpp` during `PluginHost::load()`, despite JUCE's `VSTPluginInstance::prepareToPlay` already sending `effMainsChanged`/`effStartProcess`. Rendering still completes correctly (confirmed via WAV output), so this looks like a DPF/JUCE VST2 lifecycle-ordering quirk rather than a testhost bug, but it hasn't been root-caused - worth a closer look if it turns out to affect correctness (not just log noise) for some other plugin. - [ ] **`WavAudioFormat`'s base-class doc comment says channel count "must be either 1 or 2"** (`AudioFormat::createWriterFor`'s Doxygen comment). `WavRecorder` passes through whatever `PluginHost::getNumOutputChannels()` reports with no clamping, and this has worked fine for the 1- and 2-channel plugins tested so far - but a plugin with more than 2 output channels hasn't been tried, so it's unconfirmed whether JUCE's WAV writer actually enforces that limit or the doc comment is just generic/stale boilerplate shared across format subclasses. ## Nice-to-have (not planned, just noted) - [x] A `--list-params` or similar introspection mode (print every parameter's index/name/current value) would help writing new scenario JSON files without cross-referencing the plugin's own GUI or source. Done: `--printParams` (prints `PARAM ` for every parameter, after any initial `--patch`/`--bank` load) - added to make the patch/bank round-trip regression tests in `tests/` possible; only prints values, not names, so cross-referencing the plugin's own parameter-name list is still occasionally needed.